The "clown" a couple posts above (John Wayne Gacy) was Chicago's second serial killer.
America's First known serial killer was; Herman Webster Mudgett - aka; Dr. Holmes - aka; H.H. Holmes.
(Killings between 1893 and 1895 during Chicago's first World's Fair)
Mudgett’s criminal career started as a medical student who stole corpses from the University of Michigan. He used those corpses to collect insurance money on policies taken under fictitious names
Dr. Holmes then started a drug store empire and constructed a huge hundred-room mansion with trap doors, lime pits, fake walls, acid vats, and secret entrances. (for those of you in the Chicago area, his mansion was located in what is today known as the Englewood neighborhood of Chicago).
Modus Operandi
He would rent rooms to visitors and then try and collect the insurance when they were killed there. He also used to lure women to his “torture castle,” promising marriage. He would then throw them down the elevator shaft and gas them to death. But before he did that he would force them to sign all their life savings over to him.
Killings
His huge castle with secret passages had a drugstore and other shops on the ground floor and the upper areas were used as his office. There were more than a hundred rooms without windows, and there were doorways that opened into brick walls. There were also stairways to nowhere, doors that could not be opened from the inside and several other such oddities. This was to become his killing den.
It was here that the killing spree sprouted over a period of three horrible years. Female victims were mostly his employees who were required to take a life insurance policy where Holmes would pay the premiums. Soundproof rooms with gas lines fitted in were used to kill people. These victims were asphyxiated and their screams went unnoticed as they suffocated. There was a chute that took the bodies to the basement, where some bodies were dissected, flesh removed and turned into skeletal models. He sold these skeletons and other organs to medical schools.He also performed illegal abortions in the castle and many of his patients died.
Sentence
Eventually Chicago police grew suspicious about the activities in the castle and when he knew he was getting caught, he burnt the castle and vanished. Remains of more than
two hundred people were found in the charred debris. He was later caught and hanged.
Actor Tom Hanks owns the rights to his story.